scholarly journals Structure and photocatalytic properties of sintered TiO2 nanotube arrays

2018 ◽  
Vol 50 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Jelena Vujancevic ◽  
Andjelika Bjelajac ◽  
Jovana Cirkovic ◽  
Vera Pavlovic ◽  
Endre Horvath ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Tio2 Nanotubes ◽  
Elevated Temperatures ◽  
Uv Light ◽  
Tio2 Nanotube ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Tio2 ◽  
Nanotube Films

One-dimensional (1D) TiO2 nanotubes perpendicular to the substrate were obtained by electrochemical oxidation of titanium foil in an acid electrolyte. In order to alter the crystallinity and the morphology of films the as-anodized amorphous TiO2 nanotube films were sintered at elevated temperatures. The evolution of the morphology was visualized via scanning electron microscopy (SEM), while the crystalline structure was investigated by X-ray diffraction (XRD) and Raman spectroscopy. The chemical composition was studied by X-ray photoelectron spectroscopy (XPS). The effects of crystallinity and morphology of TiO2 nanotube (NTs) films on photocatalytic degradation of methyl orange (MO) in an aqueous solution under UV light irradiation were also investigated. The TiO2 nanotubes sintered at 650?C for 30 min had the highest degree of crystallinity and exhibited the best photocatalytic activity among the studied TiO2 nanotube films.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

Oxidation of Alloy-X in Subcritical, Transition, and Supercritical Water

CORROSION ◽  
10.5006/3881 ◽  
2021 ◽  
Author(s):  
Zachary Karmiol ◽  
Dev Chidambaram
Keyword(s):  
Supercritical Water ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Elevated Temperatures ◽  
Subcritical Water ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
Before And After

This work investigates the oxidation of a nickel based superalloy, namely Alloy X, in water at elevated temperatures: subcritical water at 261°C and 27 MPa, the transition between subcritical and supercritical water at 374°C and 27 MPa, and supercritical water at 380°C and 27 MPa for 100 hours. The morphology of the sample surfaces were studied using scanning electron microscopy coupled with focused ion beam milling, and the surface chemistry was investigated using X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy before and after exposure studies. Surfaces of all samples were identified to comprise of a ferrite spinel containing aluminum.

Hydrothermal Synthesis and Photocatalytic Properties of Flower-Like CdS Nanostructures

2011 ◽  
Vol 335-336 ◽  
pp. 460-463 ◽  
Author(s):  
Hong Mei Wang ◽  
Da Peng Zhou ◽  
Yuan Lian ◽  
Ming Pang ◽  
Dan Liu
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Sulfur Source ◽  
X Ray Diffraction ◽  
Facile Hydrothermal Method ◽  
X Ray ◽  
Transmission Electron ◽  
Cds Nanostructures

Hexagonal flower-like CdS nanostructures were successfully synthesized through a facile hydrothermal method with thiourea as sulfur source. By combining the results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), the structural and morphological characterizations of the products were performed. The photocatalytic activity of CdS nanostructures had been tested by degradation of Rhodamine B (RB) under UV light compared to commercial CdS powders, which indicated that the as-syntherized CdS nanostructures exhibited enhanced photocatalytic activity for degradation of RB. The possible growth mechanism of CdS nanostructures was proposed in the end.

Platinum Reduction Study on Pt/C Electro-catalysts for PEMFC

2013 ◽  
Vol 16 (3) ◽  
pp. 141-145
Author(s):  
M.L. Hernandez-Pichardo ◽  
R. Gonzalez-Huerta ◽  
P. del Angel ◽  
E. Palacios-Gonzalez ◽  
M. Tufiño-Velazquez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Reducing Agents ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Platinum Species ◽  
Scanning Electron

Platinum reduction on Pt/C catalysts was studied on samples prepared by the impregnation method using different Pt precursors and reducing agents such as ethanol, sodium borohydride and ethanol-UV light (photo-assisted reduction), in order to compare the efficiency of the different reducing agents. The influence of the reduction level of the platinum species on the electrochemical behavior of these catalysts has been determined. The catalysts were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and linear and cyclic voltammetry. The results show that the reduction level depends mainly on the platinum precursor. Moreover, it was found that the higher electrochemical activity was found using catalysts reduced with ethanol, whereas by using NaBH4 as the reducing agent, the total reduction of the platinum precursor is very difficult in same synthesis conditions. The analysis of the XPS results shows that samples reduced with ethanol presented the lower PtOx/Pt reduction ratio.

Synthesis of Nitrogen and Sulfur Codoped TiO2 and its Better Efficient Degradation of Organophosphorus Pesticides

2011 ◽  
Vol 183-185 ◽  
pp. 1787-1790
Author(s):  
Guang Sheng Chen ◽  
Si Yao Guo ◽  
Feng Zhang ◽  
Shi Miao Dong ◽  
Song Han
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Degradation Rate ◽  
Uv Light ◽  
Organophosphorus Pesticides ◽  
Organophosphorus Pesticide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Efficiency

N, S codoped titania with high photocatalystic properties were prepared by hydrothermal method. The resulting materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy. N, S codoped titania displayed a better degradation rate of organophosphorus pesticide under visible light irradiation. The utility of N, S codoped TiO2 as a photocatalysis over undoped titania entirely, whether the requirement for visible-light functionality, even if at low efficiency, outweighs a modest drop in the efficiency of catalysis using UV light.

scholarly journals Oxidation Stabilization of ZrFe Alloys in Nitrogen Gas Atmosphere

2021 ◽  
Vol 59 (10) ◽  
pp. 754-760
Author(s):  
Kwangbae Kim ◽  
Saera Jin ◽  
Yesol Lim ◽  
Hyunjun Lee ◽  
Seonghoon Kim ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Elevated Temperatures ◽  
Nitrogen Atmosphere ◽  
Metallic Silver ◽  
X Ray Diffraction ◽  
Alloy Specimen ◽  
Surface Color ◽  
Nitrogen Gas ◽  
X Ray ◽  
Gas Atmosphere

A porous ZrFe alloy specimen was prepared as a 6 × 3 mm (diameter × thickness) disk. The reaction of the ZrFe alloy was confirmed while the whole system was maintained at a target temperature, which was increased from 150 oC to 950 oC in a 99.999% low purity nitrogen atmosphere, consisting of 10 ppm of impurity gas. Surface color, pore size, stabilized layer, and phase change were confirmed with optical microscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Micro-Raman, according to temperature. The surface color of the ZrFe alloy changed from metallic silver to dark gray as the temperature increased. In the EDS and XPS results, nitrogen component was not observed, and oxygen content increased on each surface at the elevated temperatures. In this way, the ZrFe alloy was stabilized in a low purity nitrogen atmosphere, preventing rapid nitride reactions.

Hydroxyapatite Coatings Produced by Right Angle Magnetron Sputtering for Biomedical Applications

2007 ◽  
Vol 1008 ◽  
Author(s):  
Zhendong Hong ◽  
Alexandre Mello ◽  
Tomohiko Yoshida ◽  
Lan Luan ◽  
Paula H. Stern ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Biomedical Applications ◽  
Titanium Substrate ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hydroxyapatite Coatings

AbstractHydroxyapatite coatings have been widely recognized for their biocompatibility and utility in promoting biointegration of implants in both osseous and soft tissue. Conventional sputtering techniques have shown some advantages over the commercially available plasma spraying method; however, the as-sputtered coatings are usually non-stoichiometric and amorphous which can cause some serious problems such as poor adhesion and excessive coating dissolution rate. A versatile right-angle radio frequency magnetron sputtering (RAMS) approach has been developed to deposit HA coatings on various substrates at low power levels. Using this alternative magnetron geometry, as-sputtered HA coatings are nearly stoichiometric, highly crystalline, and strongly bound to the substrate, as evidenced by analyses using x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). In particular, coatings deposited on oriented substrates show a polycrystalline XRD pattern but with some strongly preferred orientations, indicating that HA crystallization is sensitive to the nature of the substrate. Post deposition heat treatment under high temperature does not result in a marked improvement in the degree of crystallinity of the coatings. To study the biocompatibility of these coatings, murine osteoblast cells were seeded onto various substrates. Cell density counts using fluorescence microscopy show that the best osteoblast proliferation is achieved on an HA RAMS-coated titanium substrate. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.

scholarly journals Enhanced Solar Water Splitting Performance of 50-100 nm Pore Sized TiO2 Nanotubes

2019 ◽  
Vol 31 (3) ◽  
pp. 559-565
Author(s):  
K. Kathiresan ◽  
P. Elangovan ◽  
M.S.S. Saravanakumaar
Keyword(s):  
Water Splitting ◽  
Photoelectron Spectroscopy ◽  
Hydrofluoric Acid ◽  
Tio2 Nanotubes ◽  
Uv Light ◽  
Photoelectrochemical Performance ◽  
X Ray ◽  
Solar Water ◽  
Solar Water Splitting ◽  
The Impact

Herein, we report the fabrication of titanium dioxide nanotubes via anodization technique through with and without hydrofluoric acid . The impact of hydrofluoric acid followed by annealing effect on TiO2 nanotubes for the solar water splitting performance was examined. Prepared TiO2 samples exhibited a diameter of about 50 to 100 nm sized nanotubes and hierarchical structures and they subjected to annealing. Synthesis and annealing effects on chemical, physical and photoelectrochemical water splitting activity of TiO2 samples were scrutinized. The crystalline nature, structure and surface morphologies of prepared TiO2 photocatalysts were explored by X-ray diffraction, scanning electron microscope, and the oxidation states of both titanium and oxygen was determined by X-ray photoelectron spectroscopy. As a consequence, after annealing at 500 ºC, TiO2 thin films treated with hydrofluoric acid solution (HF-TiO2) were found to exhibit a remarkable photoelectrochemical performance than bare TiO2 nanotubes under UV light irradiation. Moreover, the mechanistic insights acquired in the current research would be beneficial to design a novel and highly efficient photocatalyst for solar water splitting systems.

scholarly journals Pyrolytic Formation of TiO2/Carbon Nanocomposite from Kraft Lignin: Characterization and Photoactivities

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 270
Author(s):  
Dhanalakshmi Vadivel ◽  
Diego Savio Branciforti ◽  
Andrea Speltini ◽  
Michela Sturini ◽  
Vittorio Bellani ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Tap Water ◽  
Aqueous Media ◽  
Pyrolytic Carbon ◽  
Kraft Lignin ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Paramagnetic Resonance ◽  
X Ray

This article reports on the formation of pyrolytic carbon/TiO2 nanocomposite (p-C/TiO2) by pyrolysis of a mixture of the P25 TiO2 and kraft lignin at 600 °C. The result was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-visible spectroscopy, electron paramagnetic resonance spectrometry (EPR), thermogravimetry (TGA) and SEM microscopy. Its photocatalytic activity was ascertained using three classes of chemical probes, namely (i) degradation of methylene blue (MB) and rhodamine-B (RhB) dyes in UV light-irradiated aqueous suspensions, (ii) depletion of phenol and (iii) degradation of antibiotics. The p-C/TiO2 nanocomposite is a strong phisisorbent of both MB and RhB nearly twofold with respect to neat TiO2. Although it is nearly twofold more photoactive toward the degradation of MB (0.091 min−1 versus 0.047 min−1), it is not with regard to RhB degradation (0.064 min−1 versus 0.060 min−1). For the degradation of phenol in aqueous media (pH 3), pristine TiO2 was far more effective than p-C/TiO2 for oxygenated suspensions (17.6 × 10−3 mM min−1 versus 4.3 × 10−3 mM min−1). Under an argon atmosphere, the kinetics were otherwise identical. The activity of the material was tested also for a real application in the degradation of a fluoroquinolone antibiotic such as enrofloxacin (ENR) in tap water. It is evident that the photoactivity of a semiconductor photocatalyst is not a constant, but it does depend on the nature of the substrate used and on the experimental conditions. It is also argued that the use of dyes to assess photocatalytic activities when suspensions are subjected to visible light irradiation is to be discouraged as the dyes act as electron transfer photosensitizers and or can undergo photodegradation from their excited states.

Z-Scheme over all Water Splitting on Rh/K4Nb6O17 Nanosheets Photocatalyst

2016 ◽  
Vol 99 ◽  
pp. 3-8
Author(s):  
Hsin Yu Lin ◽  
Yu Lin Ye
Keyword(s):  
Water Splitting ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Practical Importance ◽  
Proton Exchange ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
X Ray

Developing a photocatalysis system to generate hydrogen from water is a topic of great interest for fundamental and practical importance. In this study, hydrogen production by a new Z-scheme photocatalysis water splitting system was examined over Rh modified K4Nb6O17 nanosheets and Pt/WO3 photocatalysts for H2 evolution and O2 evolution with I-/IO3- electron mediator under UV light irradiation. The H2 evolution photocatalyst, Rh/K4Nb6O17 nanosheets with a slit like framework, was prepared by exfoliation of and proton exchange reaction. Pt/WO3 prepared by incipient-wetness impregnation method was used as O2 evolution photocatalyst. The catalysts were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy analysis (XPS), and ultraviolet-visible spectroscopy (UV-vis). These catalysts characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV-Vis). In this study, we developed a facile method of preparing K4Nb6O17 nanosheets containing Rh nanoparticles. Our results show that I- concentration and pH of reaction solution significantly influenced the photocatalytic activity. The combination of Rh modified K4Nb6O17 nanosheets with Pt/WO3 achieves a very high photoactivity (H2: 4240 O2: 1622 (μmol g-1 h-1)).

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